The present invention relates to an instrument for measuring the concentricity relation between two objects, and more particularly to an instrument for measuring the alignment of opposed mold plates in a mold press.
For many purposes, such as in molding an article, it is necessary to provide accurate alignment between two objects, such as two parts of a mold. This is particularly desirable in a mold for molding recorded information discs. The information on the disc is generally along a spiral track on each surface of the disc and it is highly desirable that the tracks on both sides of the disc be concentric with respect to the center of the disc. Thus, when the mold plates of the mold are mounted in a press it is highly desirable to be able to accurately align the plates with respect to each other. Therefore, it would be desirable to have an instrument which can be used to quickly and accurately align the two mold plates. In addition, the instrument would have to be relatively small in size because of the limited space provided between the mold plates in the press.